From 2021, Mozilla Firefox has Full Cookie Protection, which prevents cookies from being tracked by cookies. These files are downloaded from sites and can be used to show what data the user is getting from other sources he is searching for, etc. can follow. If this feature was optional before, now the developers have forcibly enabled it.

From now on, access to a particular cookie will be possible only on the site from which it was downloaded. This will make it difficult to collect information about the user. For example, if a user is looking for a place to buy new sneakers, Total Cookie Protection does not allow third-party sites to learn about this and display ads offering to buy shoes. At the same time, Total Cookie Protection does not block ads, it simply does not allow you to collect a lot of information about user requests.

This feature is already enabled for all Firefox users on macOS and Windows computers. It will appear on Android in the future, but not on iOS as Apple requires all third-party browsers to be based on the WebKit engine like Safari. An interpreter extension was previously released for Firefox. Source